What type of materials can be challenging to test effectively using Eddy Current Testing?

Eddy Current Testing (ET) can face significant challenges when testing coated or insulated materials. This is primarily due to the presence of the coating or insulation layer, which can interfere with the generation and measurement of eddy currents in the underlying conductive material. When the tester attempts to probe these materials, the eddy currents may be attenuated or distorted as they pass through the non-conductive layer. This can lead to inaccurate readings or difficulties in detecting defects in the underlying material since ET relies on the interaction of eddy currents with the material's conductivity and geometry. Coated surfaces may also mask flaws that exist in the substrate, making it harder to achieve a reliable assessment of the material's integrity.

Conductive metals are typically well-suited for Eddy Current Testing, as the method is designed to take advantage of electrical conductivity. Thin-walled components can be tested, although special considerations related to probe selection and frequency may be needed; they do not inherently present the same challenges as coatings. High-temperature alloys can be tested, although specific equipment may be necessary to handle the effects of temperature on the testing process, such as changes in conductivity, but this is a different consideration compared to the interference caused by coatings.